Currently, United States military personnel use the U.S. Air Force Resolution Chart of U.S. Pat. No. 4,607,923 issued to Task et al. in 1986 when evaluating or adjusting night vision goggle devices. This resolution chart is now a standard for use by U.S. and allied military units performing night vision goggle missions. This chart has a series of increasingly finer pairs of black and white bars, bars that, when viewed through night vision goggles, allow maintenance personnel to evaluate and adjust the image quality and allow the war fighter to personally perform night vision adjustments such as objective lens focusing, interpupillary distance selection, tilt angle adjustment, eyepiece selection and battery checking prior to a night vision mission. For language convenience purposes the several functions accomplished with aid of the present invention may be referred-to as “tuning” of a night vision device.
Proper use of this resolution chart however requires it to be precisely irradiated at several different levels, levels corresponding to no moon presence, quarter moon presence, half moon presence and full moon presence during usage. This chart usage irradiance is also preferably accomplished with the aid of an irradiance-measuring instrument such as a photometer or a radiometer or less preferably with human estimation of irradiance level. Photometer and radiometer instruments range in value from $5,000 to $28,000 or greater as may be observed in the catalog or on the web site of one supplier of such instruments, Hoffman Engineering Corporation of Stamford, Conn., http://www.hoffmanengineering.com. Such instruments are also generally unsuited for use under military field conditions as is dictated by their cost and their substantially fragile nature.
The present invention is believed to provide an answer for these difficulties.
The U.S. Pat. No. 4,607,923 and each other patent document and reference document identified herein are also hereby incorporated by reference herein.